But I got the idea:
I have some contact microphones and pretty strong transducers, would it work if I miked the instrument, say an acoustic guitar from the soundboard with contacts, tweaked the delay to 0ms and fed the output back to the soundboard to actually make the instrument play louder?

Taika-Kim wrote:My computer went boom, so for now can't do anything with audio.

But I got the idea:I have some contact microphones and pretty strong transducers, would it work if I miked the instrument, say an acoustic guitar from the soundboard with contacts, tweaked the delay to 0ms and fed the output back to the soundboard to actually make the instrument play louder?

Sounds fun, give it a go and report back!
May not give you exactly the results, but it should be interesting. If nothing else you might get some crazy noise out of it.